1. Field of the Invention
The present invention is related to nebulization systems utilized in medical inhalation therapy and, more particularly, is concerned with the provision of a radioaerosol nebulization chamber utilized in conjunction with an ultrasonic nebulizer for improving the efficiency of delivery of the nebulizer aerosol to the patient.
2. Description of the Prior Art
Scintigraphy is a diagnostic technique in which a two-dimensional picture of a bodily radiation source is obtained by the use of radioisotopes. Radioaerosol lung scintigraphy is one technique available for measuring the distribution of ventilation in patients having respiratory diseases, and has certain advantages over other measurement techniques. For example, radioaerosols are relatively inexpensive to produce, may be delivered at tidal volume respiration, result in high information-density aerosol inhalation images which may be obtained in multiple projections to allow precise correlation with the distribution of perfusion.
Despite such advantages, radioaerosol lung scintigraphy has not been widely adopted. A major objection to the technique is the heretofore inefficient and unpredictable nature of aerosol delivery. Larger aerosol particles tend to deposit in the trachea and major bronchi, and tend to reduce the likelihood of obtaining ventilatory distribution obtainable by other techniques.
Previous studies have indicated that the major factors effecting pulmonary distribution of aerosols are the particle size, the aerosol concentration, the air flow rate, and the airway turbulence. Such studies include, for example, an article by Taplin et al which appeared in the Journal of Nuclear Medicine, Vol. 7, pgs. 77-87, entitled "Lung Scanning Following Radioaerosol Inhalation" (1966); and an article by Mitchell in Vol. 82 of American Review of Respiratory Disease, pgs. 627-629: "Retention of Aerosol Particles in the Respiratory Tract" (1960).
Prior art patents uncovered during the course of a preliminary examination search of which I am aware include the following: U.S. Pat. Nos. 3,172,406; 3,301,255; 3,630,196; 3,744,722; 3,771,721; 3,836,079; 3,842,833; and 3,892,235. However, none of the foregoing teach devices which are specifically addressed towards the problems above-enumerated, which are peculiar to radioaerosol pulmonary ventilation distribution techniques, and which also apply to distributive techniques for non-radioactive aerosols which are also used therapeutically in various lung diseases. That is to say, common deficiencies noted with respect to the prior art devices has been their failure to provide efficient and predictable aerosol delivery to the lungs, while preventing deposition of larger aerosol particles in the trachea and major bronchi to thereby improve the overall delivery efficiency.